Refrigerating apparatus



Jan. 11, 1944.

R. E. GOULD ETAL REFRIGERATING APPARATUS Filed Sept. 28, 1940 3Sheets-Sheet l om om *n om 3 INVENORa AoRNEY Jan. ll, 1944. R. E, GoULDETAL REFRIGERATING APPARATUS Filed Sept. 28, 1940 3 Sheets-Sheet 2 8 lINVENTOR@ ------,.ilwdlJ .1 P 1TEK Imm l munlullllllllnmlll- ATTORNEYSJan* 119 R. El. GOULD ETAL REFRIGERATING APPARATUS INVENTORS M Bw W MATTORNEY:

Patented Jan.v 11, 1944 REFRIGERATING APPARATUS Richard E. Gould andCharles F. Henney, Dayton, Ohio, assignors to General MotorsCorporation, Dayton, Ohio, a corporation of Delaware ApplicationSeptember Z8, 1940, Serial No. 358,873

3 Claims.

This invention relates to refrigerating apparatus and more particularlyto refrigerating apparatus adapted to condition the air for thepassenger compartment of a vehicle or the like.

One object of this invention is to provide an improved refrigerantliquefying unit in which the compressor may be directly driven from aninternal combustion engine.

Still another object of this invention is to provide an improved shaftseal arrangement for use with a high speed compressor.

A further object of this invention is to provide an improved arrangementfor cooling the shaft seal by means of liquid refrigerant.

A still further object of this invention is to provide means forrecondensing refrigerant which may have been evaporated in cooling theshaft seal.

Another object of this invention is to provide an improved controlcircuit for use in the above mentioned refrigerating system.

It is also an object of this invention to improve upon the generalarrangement of parts in a refrigerating system of the type adapted to bemounted on a vehicle.

Another object of this invention is to provide an improved means forunloading the compressor so as to facilitate cranking of the compressorengine.

Still another object of this invention is to utilize one chamber of aheat interchanger as an unloading chamber.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein a preferred form of the present invention is clearlyshown.

In the drawings:

Fig. l is an elevational view with parts broken away showing thearrangement of the elements on a bus;

Fig. 2 is a top view showing the general arrangement of the refrigerantliquefying unit;

Fig. 3 is a fragmentary sectional view taken on the line 3-3 of Fig. 2,showing diagrammatically the refrigerant fiow circuit; and

Fig. 4 is a diagrammatic view showing the electrical controls for therefrigerating apparatus.

In designing air conditioning apparatus for use on a bus or the like, itis important to conserve on space and weight and at the same time, it isalso important to provide refrigerant liquefying apparatus, whichrequires a minimum amount of servicing from time to time. It is alsoimportant to design the refrigerating apparatus so side wall of the bus.

that the refrigerant liquefying mechanism may be disconnected from therefrigerant evaporator without disturbing the supply of refrigerant inthe system and without contaminating the interior of the refrigerantflow path.

In Fig. l, of the drawings, we have shown a preferred embodiment of ourinvention in which the reference numeral it is used to designate aconventional passenger bus having a main passenger compartment ii. Anair duct I2 is provided beneath the floor of the passenger compartmentand communicates with the passenger compartment it through return airpassages iii provided in the oor of the passenger compartment il. Theair to be conditioned is circulated through the duct i2 by :means of ablower unit i6 mounted Within an enlarged portion of the duct i2. Theblower unit i6 withdraws air from 'the passenger compartment ii throughthe openings i4 and discharges the air into a vertical duct i8 whichcommunicates with a horizontally disposed air duct t0 mounted directlyabove the normal head room of the bus. The duct 20 is provided withlouvers such as 22 for directing air into the main passenger compartmentand louvers 24 for directing air into the drivers compartment located atthe front of the bus. While only one set of air ducts i8 and 2U can beseen in Fig. 1, it is to be understood that a similar set is provided onthe other side of the bus whereby the conditioned air discharges intothe passenger compartment from both sides of the bus. The desired amountof fresh air may be introduced into the duct l2, through the fresh airgrille 26 provided in the The mixture of fresh air and recirculated airis caused to fiow through an air lter 28 and a refrigerant evaporator 30also located in the enlarged portion of the air duct l2.

Liquid refrigerant is supplied to the evaporator 3G by the refrigerantliquefying apparatus mounted beneath the air duct I2. The refrigerantliquefying apparatus comprises an internal combustion engine 34 which isdirect connected to a rotary compressor unit 36. The internal combustionengine 36 also drives a fan 38 which circulates air in through the inlet52 and out through the outlet 4D. The internal combustion engine 34 andits associated elements are mounted on a frame E4 which also supportsthe engine radiator 46 and the refrigerant condenser d8. The frame '36is removably and resiliently mounted on the bus by means of a pluralityof rubberlike mounting's.

Referring now to Fig. 3 in which the refrigerant ow circuit isdiagrammatically shown, it is apparent that the compressed refrigerantleaving the compressor 38 via the line 52, first enters the condenser 48in which the compressed refrigerant vapor is converted into liquidrefrigerant. The liquid refrigerant leaves the condenser 48 through theline 5B. 'I'he liquid refrigerant flowing in line 56 discharges into ashaft seal cooling chamber 58 through the opening 18 located adjacentthe bottom of the chamber 88. As shown in Fig. '3, the compressor 38comprises a conventional rotary compressor unit 88 which discharges thecompressed refrigerant at 82 into the chamber 84 formed`by the outershell 85. The compressor operating shaft 88 which is an extension of theengine shaft, is supported in a Inasmuch as the compressor is directconnected to the internal combustion engine, it is desirable to providemeans for unloading the compressor after each shut-down so as to avoidhaving to crank the engine when the compressor is under load. For thispurpose, I have provided asmall capacity by-pass line 88 between thecompressor discharge line 82 and the outer chamber of the heatinterchanger 84. The bypass line 98 is in the form of a very small tubewhereby the quantity of refrigerant by-passed through the line 98 doesnot materially reduce the capacity of the refrigerant system while thecompressor is in operation. The small capacity bearingelement 88 securedto the casting 78 by means of bolts 1|. The member 18, in turn, isbolted to the engine housing by means of bolts 12.

In order to simplify this disclosure, the details of the gasketswhichare used for sealing the joints between the main compressor casing88 and the elements 88 and i8 have been omitted. It is to be understood,however, that the joints between these elements are refrigerant tight.In order to prevent the escape of refrigerant along the shaft 68, aconventional shaft seal unit 'I8 has been provided. Inasmuch as shaftseals of this general type are old and insasmucli as the specificdetails of the shaft seal are immaterial. the details of the shaft sealstructure have not been shown.

Inasmuch as shaft seals of all types will generate a certain amount ofheat especially at high shaft speeds and inasmuch as it is desirable toprovide a direct connection between the engine and the compressor and tooperate the compressor at high speeds, it is important to provide someunfailing means for cooling the shaft seal 14. In order to cool theshaft seal 14 all of the liquid refrigerant leaving the condenser 58 iscaused to flow directlyinto the chamber 58 surrounding the maincompressor bearing and the shaft seal mechanism 74. The liquidrefrigerant discharges into the cavity 58 at the point 18 and leaves thecavity at 88. inasmuch as the heat generated is at times sufficient tovaporize a portion of the liouid refrigerant flowing through the cavity58, the refrigerant leaving the cavity 58 is circulated through theinner section 82 of a heat interchanger 84 which also functions as areceiver for the condensed liquid refrigerant.

The liquid refrigerant leaving 82 flows through a conventional fixedrestrictor 88 before entering the evaporator 38. 'I'he fixed restrictor88 may be any one of several well known types, such as a long length ofsmall diameter capillary tubing or it may be of the type disclosed inPatent No. 2,863,745. A check valve 88 is provided at the outlet of theevaporator so as to prevent the reverse flow of the refrigerant backinto the evaporator. The refrigerant vapor leaving the evaporator 38 isat a relatively low temperature andis passed through the heatinterchanger 84 wherein it serves to cool the refrigerant flowingthrough the inner portion 82 of the heat interchanger. Any refrigerantwhich may have been evaporated in the chamber 58 is recondensed in theinterchanger. The refrigerant vapor coming from the evaporator 38 flowsfrom the heat interchanger 84, through pipes 98, check valve 92 andthence the inlet S4 of the pump 88. The check valve 92 prevents any ofthe lubricant 93 from backing up into the interchanger 84 during the offcycle.

lay-pass4 does, however, serve to equalize the pressure between thecompressor outlet line 82 and the heat interchanger 84 in a relativelyshort period of time during any period of shut-down. By virtue of the'check valve 88, the equalization of pressure between the high side ofthe compressor and the low side of the' compressor is limited to only asmall` portion Vof the refrigerant circuit. y

Referring now to Fig. 4, in which the electrical control circuit isshown, the reference numeral |88 designates a storage battery which maybe kept charged by the bus generator in the usual well known manner.Reference numeral |82 designates a'manual switch which serves to turn onand oil? the entire air conditioning system. Reference numeral |84designates a manual switch provided in the blower motor circuit. Uponclosing of theswitches |82 and |84, the blower motor I6 is energized andwill continue to circulate air within the bus so long as the switchesremain closed. Reference numeral |88 designates a manual switch whichcontrols the main thermostats ||8 and ||2 which in turn control theoperation of the'internal combustion engine 34. Closing of the switches82 and |88 also energizes a signal light. |88 which may, for

. example, be mounted in the drivers compartment. Whenever the light'|88 is lit this indicates that the switches |82 and |88 are both closed.The thermostat |8 is set to operate at a higher temperature than thethermostat l2. The thermostat 8 controls the circuit to solenoid coil H4which when energized serves toincrease the speed of the engine byopening the engine throttle so as to increase the capacity of therefrigerating system. The low temperature thermostat 2 is in'series withthe engine ignition coil I8. The thermostats ||8 and ||2 are preferablyplaced within the passenger compartment or in the return air stream.Upon closing of the thermostat ||2, the ignition coil ||8 is energized.In order to start theV engine, however, it is necessary for the operatorto manually close the normally open starter push button ||8 which isarranged in series with the solenoid coil |28'. Energization of the coil|28 closes the switch |22 which is arranged in circuit with theconventional engine starter motor |24. The starter motor |24 serves tocrank the vengine 84 in the usual well known manner. as the engine 34starts, 'the push button ||8 is releasedl so as to open the circuittothe starter motor at |22. As the engine 84 gains speed thisautomatically causes opening of the switch |28 arranged in series withthe indicator light |28.

.'Ihe switch |26 may be of the type in which the air circulated by theengine fan 88 strikes a wind vane |21 carried by the switch |28 therebyopening the switch.

By virtue of the above arrangement, whenever Just as soon cuit to coillll whereby the speed of the engine will be reduced. If operation of theengine 34 at the reduced speed provides more than the necessary amountof refrigeration, the temperature within the passenger compartment willfinally drop below the value at which the thermostat ||2 is set, wherebythe circuit to the ignition coil IB will be opened and the engine willbe stopped. After each period of shut-down the thermostat ||2 is thefirst to close, but inasmuch as it is not practical to crank the engineat too frequent intervals the operator does not restart the engine untilthe thermostat ||0 is also closed at which I time the signal lamp |28gives the operator notice that the temperature in the passengercompartment is above the desired value and that the engine should bestarted. It is possible, however, for the operator to restart theengine, if desired, any time after the thermostat ||Z has closed. If theengine is started before thermostat ||0 is closed the engine willoperate at the reduced speed since the coil ||I will not be energizedunder such conditions.

While I have disclosed two separate thermostats no and nz, it is withinthe purview or this invention to use, a single thermostat which closes afirst circuit to the ignition coil at one temperature andwhich closes asecond circuit to the throttle control coil ||4 at a slightly highertemperature. In order to simplify this disclosure we have shown switches|02, |04, |06 and ||8 as manually operated switches whereas theseswitches may be operated in response to the temperature'or humidity ofeither the outside air or the inside air.

In a refrigerating system of the type adapted to be installed on a bus,it is frequently desirable to remove the engine and the compressor unitfrom the bus for inspection and repair purposes. In order to facilitatethe removal of the engine and the compressor unit from the bus withoutdisturbing the refrigerant charge in the refrigerant circuit, a specialseparable connector |60 is provided, as' shown in Fig. 2. The connector|50 includes a first dual valve housing |50 which carries 'a pair ofmanually operable valves |52 and a second dual valve housing |58 whichcarries a pair of manually operable valves |54. The

housings |55 and |58 are normally held together by the bolts |50. Thevalves are normally open at all times when the refrigerating system isin operation but are adapted to be closed when it is desired todisconnect the evaporator from the rest of the system so as to lmake itpossible to remove the rest ofthe system from the bus. The arrangementis such that the condenser 48, which is supported on the main frame 44is removed along with the engine 34 and compressor l0. BY closing thevalves |52 and |54, the refrigerant connections between the evaporatorand the rest of the system may be disconnected without disturbina therefrigerant and lubricant charge within the system and withoutintroducing any inert gas or moisture into the refrigerant circuit.

It is common practice in the refrigeration art to provide a driercartridge somewhere in the -refrigerant circuit for absorbing any waterwhich may be found in the refrigerant system. Cartridges of this typeare well known in the art and usually comprise a body of anhydrouscalcum sulphate. These cartridges are of necessity small and can absorbonly a limited amount of moisture. I have placed a removable cartridge|60 of this type between the two sections |56 and |58 of the connector|50 whereby upon disconnecting the refrigerant circuit at |50, thecartridge |60 becomes accessible and may be reactivated or replaced sothat upon reconnecting the refrigerant system a new cartridge may beinserted which is capable of removing any moisture which may have foundits way into the refrigerant circuit.

By virtue of the above described arrangement, the refrigerant liquefyingapparatus may be disconnected from' the evaporator any number of timeswithout disturbing the refrigerant charge and without destroying theeffectiveness of the drying cartridge.

While the form of embodiment of the invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows: l. In combination, a compressor includinga drive shaft, a shaft seal therefor and a shaft seal cooling cavity, acondenser, an evaporator, a heat interchanger including a rst passageand a second passage, refrigerant flow connections for directing thecompressed refrigerant leaving the compressor through the condenser, theshaft seal cooling cavity, the rst passage of the heat interchanger, theevaporator, the second passage of the heat interchanger and thereafterinto the inlet of the compressor, means preventing reverse flow 'ofrefrigerant from the second passage of said interchanger to saidevaporator, and means for unloading said compressor including means forequalizing the pressure between the second passage of said heatinterchanger and the outlet of said compressor.

2. In combination, a compressor including a drive shaft, a shaft sealtherefor and a shaft seal cooling cavity, a condenser, an evaporator, aheat interchanger including a first passage and a second passage, andrefrigerant ilow connections for directing the compressed refrigerantleaving the compressor through the condenser, the shaft seal coolingcavity, the first passage of the heat interchanger, the evaporator, thesecond passage of the heat interchanger and thereafter into the inlet ofthe compressor.

3.f In combination, a compressor including a drive shaft and a shaftseal therefor, a condenser, an evaporator, refrigerant flow connectionsbetween said compressor, condenser and evaporator, said refrigerant owconnections including means for conducting liquid refrigerant from saidcondenser into thermal exchange with'said shaft seal and thereafter intothermal exchange with refrigerant vapor flowing from said evaporator tothe inlet of said compressor.

CHARLES F. HENNEY. RICHARD E. GOULD.

